The present disclosure relates generally to the field of antenna systems. More specifically, the present disclosure relates generally to the field of time delay units for feed manifolds including but not limited to, feed manifolds for phased array antenna systems or electronically scanned array (ESA) antenna systems, such as active electronically scanned array (AESA) antenna systems.
Antenna arrays are utilized with transceivers. As used in this application, the term transceiver refers to an electronic device embodied as a transmitter, a receiver or a transmitter/receiver. The antenna array can be steered by using variable phase shifters coupled to respective antenna elements in the antenna array to direct the antenna at a pointing angle. The phase shifters can be variable phase shifters which provide a set of phase delays in response to a set of commands to direct the antenna to appropriate pointing angles without physically moving the antenna elements.
In certain applications, transceivers using phase shifters can be susceptible to beam squint. The beam squint can be caused by phase shifters which do not have a constant response with respect to frequency. For example, conventional phase shifters generally have a phase delay which changes with changes in frequency (τ=−δΦ/δf). The change in phase shift or phase delay due to frequency can adversely affect the accuracy of the pointing angle of the antenna. For example, the pointing angle can change by more than 90 degrees across a frequency range between 2.0 and 18.0 Gigahertz (GHz) due to the small consistent operational band width of the phase shifters. In ultra wide band (UWB) applications, problems caused by the response of the variable phase shifter to frequency are more pronounced. Accordingly, a severe pulse distortion/dispersion can result from the use of a UWB AESA with phase shifters. In addition, operating active electronic scanning arrays with phase shifters in the UWB can result in pattern/gain corruption, wave form modulation distortion, loss of range/link margin, loss of directionality and loss of data rate due to the small consistent operational bandwidth of the variable phase shifter.
Time delay units (TDUs) can be used instead of phase shifters to direct the antenna to a pointing angle without significant beam squint issues. However, time delay units are physically large in size. The large size of the time delay unit with respect to the aperture lattice spacing fails to prevent the creation of false main beams. Further, conventional time delay units can require prohibitively excessive direct current (DC) power. In digital implementations, conventional time delay units can introduce quantization errors. The quantization errors can result in high side lobe levels for an active electronically scanned array.
Thus, there is a need for an antenna system which is not as susceptible to beam squint and/or grating lobes. Further, there is a need for a time delay unit with analog like behavior. Further still, there is a need for a time delay unit for an antenna system with at least one of: reduced size, reduced power consumption, and reduced quantization errors. Further still, there is a need for a reduced size feed manifold that does not include large time delay paths. Further still, there is a need for active time delay units which are smaller, lighter, and require less power. Yet further still, there is a need for a method of providing an active radio frequency integrated circuit-based manifold with time delay units. There is a further need for a miniature N-way feed manifold with integrated time delay units. There is a further need to integrate time delay units on a radio frequency integrated circuit (RFIC) for one dimensional or two dimensional AESA beam scanning.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.